Robust, succulent to leathery, arborescent or acaulescent perennials. Trunk unbranched, tall or short (or 0). Leaves in a dense rosette, fleshy or leathery, margins with conspicuous well-spaced spines and entire between, or with minute close teeth throughout. Inflorescence a large terminal pyramidal panicle; scape tall. Flowers bisexual, whitish or greenish-white, numerous along branches, solitary or in small fascicles of 2-3, with scarious bracts; flowers often replaced by bulbils; segments connate in short tube, lobes spreading. Stamens usually < segments, inserted at base; filaments with cushion-like swelling at base; anthers dorsifixed. Ovary inferior, 3-locular; style 3-angled and thickened below, stigma small; ovules many in each locule. Seeds flat, black. Some spp. reproducing only by bulbils and not forming seed. Spp. c. 20, of tropical America. Adventive sp. 1.